Hi Marcus, Hi Sylvain,
Thank you for your response. I continue to get these ULLLLLLLLLLLLLLLL even on a PC with really high specs.
Please find below my answers to your questions.
>> Do you use timed_commands?
Yes, I do. In the python script, I simply use get_time_now() to query the times of both the Sink and the Source. Then, I convert this to a format understandable to python and I keep hold of the greater time of the two, I call it start_delay. Then, using set_start_time(), I make sure that both the Sink and the Source start at time start_delay.
Is there any problem with my timed_commands?
>> What are your RX and TX sampling rates?
It's 100e06/256 = 390,625 Hz for both Tx and Rx.
>> From your network throughput, I'd assume your using 4x 3.3MS/s, is that correct?
I am using four Rx channels, and just one Tx channel. Based on the NW history in the link below,
My throughput is around 1.6 MB/s for each channel. This is set automatically by GNU Radio. Do I need to adjust it?
Marcus Müller (Guest)
on 2015-01-07 15:24
Hello Sylvain, hello Khalid,
these could be underruns (U) and late (L) packets, as reported by UHD,
used via gr-uhd; however, seeing so many L's is a very uncommon pattern;
Do you use timed_commands? What are your RX and TX sampling rates? From
your network throughput, I'd assume your using 4x 3.3MS/s, is that
Could you share the whole output of your program's run, not only the
In the terminal and while using a powerful PC (please see the
I am occasionally getting capital U's and L's when running GNU Radio
one Tx and 4 Rx channels (Here is a sample of what I am getting:
Please note that I am using timed-commands to start both the Tx and Rx's
the same time. When I check the System Monitor while GNU Radio is
(please see the attachment), the CPU history and RAM usage seem to be
Also, swap memory is disabled as shown in the attachment. What causes
issue and how to handle it? Could it be due to some instability in the
writing speed to the hard drive?
BTW, I am having the same issue for my older PC (a PC with less specs).
System Monitor tells me that my CPU usage is around 60% and my RAM usage
around 45%, however, I am getting U's and L's when I try to use four Rx
channels. Please note that the system doesn't throw lots of U's and L's
once, it is a kind of frequent where a bunch of them are thrown out
many seconds or so.
Thanks in advance for your help.